La Silla ObservatoryESO’s La Silla Observatory, 600 km north of Santiago de Chile, is a frontline astronomical facility with medium-sized and small optical telescopes, including the most successful exoplanet hunter, HARPS.

La Serena OfficeThe ESO Office in La Serena is an administrative point that supports the operation of the La Silla Observatory and serves as connection between La Silla and the rest of the ESO sites in Chile.

Paranal ObservatoryParanal Observatory, 130 km south of Antofagasta in Chile, is the flagship facility of ESO equipped with an array of four 8.2-metre telescopes, four auxiliary telescopes for interferometry and a survey telescope.

ESO Antofagasta OfficeThe ESO Office in Antofagasta is an administrative point that supports the operation of Paranal Observatory and serves as a connection between Paranal and the rest of the ESO sites in Chile.

ALMA Operations Support Facility (OSF)The ALMA Operations Support Facility, at an altitude of 2900 metres in the Chilean Andes, will serve as the focal point for the ALMA operations. Antennas are assembled here before being moved to the Array Operations Site at 5000 metres altitude.

ALMA Array Operations Site (AOS)The ALMA Array Operations Site, at an altitude of 5000 metres in the Chilean Andes, houses the ALMA antennas and the correlator, the fastest data processing system ever used at an astronomical site.

APEX Chajnantor SiteAPEX, the Atacama Pathfinder Experiment, is a 12-metre diameter antenna observing the Universe at millimetre and submillimetre wavelengths located at an altitude of 5100 metres, on the Chajnantor plateau, in Chile’s Atacama region.

Provisional ESO Offices in Garching bei MünchenBefore the inauguration of the current Headquarters Building in 1981

Schleiβheimer Straβe 17D-8046 Garching bei MünchenGermany

+49 (089) 3204 04145 (obsolete)

CERNCERN, the European Organization for Nuclear Research located in Geneva, Switzerland, hosted the ESO Telescope Project Division (TP) from the second half of 1970 until 1980 when it moved to Garching near Munich in Germany.

Geneva, Switzerland

+41 (022) 836111 (obsolete)

Hamburg-Bergedorf ObservatoryESO was founded in 1962 at the Hamburg-Bergedorf Observatory in Germany.